1. Field of the Invention
The present invention relates to image processing methods, and in particular, to an image processing method for eliminating color shifts generated in a contour region in an image obtained from an image input apparatus.
2. Description of the Related Art
In conventional image processing, an image recorded using an image input apparatus such as a digital camera or a scanner is input to a computer or the like, and the image is output from a printer.
This type of image processing has a problem in that color shifts may be generated in a contour region in the image recorded by the image input apparatus. The color shifts are generated such that a color having chroma forms a point or line in the contour portion of an almost achromatic region. This is caused by characteristics of the image input apparatus, that is, lens characteristics such as chromatic aberration, an arrangement of red, green, and blue (RGB) filters in a single charge-coupled device, or an image compression technique, etc.
The generation of the color shifts in the contour region of the image makes it impossible to output a clear recording image, which causes a substantial deterioration in the image quality.
Accordingly, it is an object of the present invention to provide an image processing method that securely eliminates color shifts generated in a contour region of an image, whereby outputting a clear image and greatly enhancing the image quality.
To this end, according to an aspect of the present invention, the foregoing object is achieved through provision of an image processing method including the steps of converting an image obtained from an image input apparatus into an Lxc2x7axc2x7b image (where L represents the gray scale axis, or luminance, and a and b represent two orthogonal axes that together define the color and saturation), obtaining a chroma image by using chroma processing to process a and b values which are chrominance-signal values in the pixels of the a and b images as saturation images, obtaining a binary image by binarizing the pixels of the chroma image, extracting the contour of the binary image, and extracting a region in which achromatization is performed by widening the extracted contour of the extracted image.
Preferably, the extracted contour of the image is widen in an arbitrary direction.
According to another aspect of the present invention, the foregoing object of the present invention is achieved through provision of an image processing method that uses RGB-image data includes the steps of converting an RGB image obtained from an image input apparatus into an Lxc2x7axc2x7b image, obtaining a chroma image by using chroma processing to process a and b values which are chrominance-signal values in the pixels of the a and b images as saturation images, obtaining a binary image by binarizing the pixels of the chroma image, extracting the contour of the binary image, extracting a region in which achromatization is performed by widening the extracted contour of the image, achromatizing the a and b images, and converting the Lxc2x7axc2x7b image processed by achromatization into an RGB image.
According to the present invention, by extracting a region in which achromatization is performed, color shifts generated in the contour region of an image can be securely extracted as the region in which achromatization is performed, and a clear image in which the color shifts are securely eliminated can be output. Therefore, the image quality can be greatly enhanced.